1. Field of the Invention
The invention concerns the catalyzed elimination of alkyl groups from disilanes comprising chlorine groups and alkyl groups in the presence of hydrogen halides.
2. Description of the Related Art
The high-boiling fraction from the reaction of methyl chloride and silicon with a boiling point above 70° C. (high boilers) contains the so-called “cleavable disilanes” dimethyltetrachlorodisilane and trimethyltrichlorodisilane, which are simple to cleave with hydrogen halide into monosilanes under amine catalysis by following known processes. The other disilanes with four, five and six methyl groups cannot be utilized in this way and therefore are also known as “noncleavable disilanes”.
A multiplicity of patents relate to converting the high boilers into monomeric alkylchlorosilanes. The processes which have been described are all very costly and inconvenient and have high apparatus requirements. For example, EP 635510 A describes cleaving the high boilers into monosilanes by using hydrogen halide and a catalyst comprising aluminum chloride at temperatures above 250° C.
H. Sakurei et al. (“Aluminum chloride-catalyzed reactions of organosilicon compounds II”, Tetrahedron Letters No. 45, pp. 5493-5497, 1966, Pergamon Press Ltd.) describe the batchwise conversion of disilanes in the liquid phase partly in the presence of acetyl chloride.